This invention is directed to transparent thermoplastic compositions having high flow and ductility, and in particular to thermoplastic compositions comprising a polysiloxane-polycarbonate copolymer and a poly(aliphatic ester)-polycarbonate copolymer, and articles prepared therefrom.
Polycarbonates, relative to other thermoplastics, are noted for their exceptional optical properties, thermal resistance, and mechanical properties such as impact strength. High flow polycarbonates, typically those having low molecular weights and/or a higher degree of branching (obtained by inclusion of trifunctional or higher monomers as branching points within the polycarbonate chain, are available where thorough mold-filling capabilities are required as for injection molding of parts with very thin dimensions and long flow lengths, where a lower flow material would not fill the mold completely before hardening, or would require excessively high mold temperatures that can result in thermal degradation and loss of desirable optical properties. In order to obtain such desirable flow properties however, the impact strength of the polycarbonate, and other mechanical properties (elongation at break, fatigue stress, and the like), may be compromised. Thin-wall and complex injection molded parts with minimal residual stress and low temperature ductility are therefore not readily prepared from existing polycarbonate materials.